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Rodofili EN, Lecours V, LaRue M. Remote sensing techniques for automated marine mammals detection: a review of methods and current challenges. PeerJ 2022; 10:e13540. [PMID: 35757165 PMCID: PMC9220915 DOI: 10.7717/peerj.13540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 05/13/2022] [Indexed: 01/17/2023] Open
Abstract
Marine mammals are under pressure from multiple threats, such as global climate change, bycatch, and vessel collisions. In this context, more frequent and spatially extensive surveys for abundance and distribution studies are necessary to inform conservation efforts. Marine mammal surveys have been performed visually from land, ships, and aircraft. These methods can be costly, logistically challenging in remote locations, dangerous to researchers, and disturbing to the animals. The growing use of imagery from satellite and unoccupied aerial systems (UAS) can help address some of these challenges, complementing crewed surveys and allowing for more frequent and evenly distributed surveys, especially for remote locations. However, manual counts in satellite and UAS imagery remain time and labor intensive, but the automation of image analyses offers promising solutions. Here, we reviewed the literature for automated methods applied to detect marine mammals in satellite and UAS imagery. The performance of studies is quantitatively compared with metrics that evaluate false positives and false negatives from automated detection against manual counts of animals, which allows for a better assessment of the impact of miscounts in conservation contexts. In general, methods that relied solely on statistical differences in the spectral responses of animals and their surroundings performed worse than studies that used convolutional neural networks (CNN). Despite mixed results, CNN showed promise, and its use and evaluation should continue. Overall, while automation can reduce time and labor, more research is needed to improve the accuracy of automated counts. With the current state of knowledge, it is best to use semi-automated approaches that involve user revision of the output. These approaches currently enable the best tradeoff between time effort and detection accuracy. Based on our analysis, we identified thermal infrared UAS imagery as a future research avenue for marine mammal detection and also recommend the further exploration of object-based image analysis (OBIA). Our analysis also showed that past studies have focused on the automated detection of baleen whales and pinnipeds and that there is a gap in studies looking at toothed whales, polar bears, sirenians, and mustelids.
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Affiliation(s)
- Esteban N. Rodofili
- School of Natural Resources and Environment, University of Florida, Gainesville, FL, United States of America
| | - Vincent Lecours
- School of Natural Resources and Environment, University of Florida, Gainesville, FL, United States of America,School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL, United States of America
| | - Michelle LaRue
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand,Department of Earth and Environmental Science, University of Minnesota, Minneapolis, MN, United States of America
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Nelms SE, Alfaro-Shigueto J, Arnould JPY, Avila IC, Bengtson Nash S, Campbell E, Carter MID, Collins T, Currey RJC, Domit C, Franco-Trecu V, Fuentes MMPB, Gilman E, Harcourt RG, Hines EM, Hoelzel AR, Hooker SK, Johnston DW, Kelkar N, Kiszka JJ, Laidre KL, Mangel JC, Marsh H, Maxwell SM, Onoufriou AB, Palacios DM, Pierce GJ, Ponnampalam LS, Porter LJ, Russell DJF, Stockin KA, Sutaria D, Wambiji N, Weir CR, Wilson B, Godley BJ. Marine mammal conservation: over the horizon. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01115] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Marine mammals can play important ecological roles in aquatic ecosystems, and their presence can be key to community structure and function. Consequently, marine mammals are often considered indicators of ecosystem health and flagship species. Yet, historical population declines caused by exploitation, and additional current threats, such as climate change, fisheries bycatch, pollution and maritime development, continue to impact many marine mammal species, and at least 25% are classified as threatened (Critically Endangered, Endangered or Vulnerable) on the IUCN Red List. Conversely, some species have experienced population increases/recoveries in recent decades, reflecting management interventions, and are heralded as conservation successes. To continue these successes and reverse the downward trajectories of at-risk species, it is necessary to evaluate the threats faced by marine mammals and the conservation mechanisms available to address them. Additionally, there is a need to identify evidence-based priorities of both research and conservation needs across a range of settings and taxa. To that effect we: (1) outline the key threats to marine mammals and their impacts, identify the associated knowledge gaps and recommend actions needed; (2) discuss the merits and downfalls of established and emerging conservation mechanisms; (3) outline the application of research and monitoring techniques; and (4) highlight particular taxa/populations that are in urgent need of focus.
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Affiliation(s)
- SE Nelms
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
| | - J Alfaro-Shigueto
- ProDelphinus, Jose Galvez 780e, Miraflores, Perú
- Facultad de Biologia Marina, Universidad Cientifica del Sur, Lima, Perú
| | - JPY Arnould
- School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - IC Avila
- Grupo de Ecología Animal, Departamento de Biología, Facultad de Ciencias Naturales y Exactas, Universidad del Valle, Cali, Colombia
| | - S Bengtson Nash
- Environmental Futures Research Institute (EFRI), Griffith University, Nathan Campus, 170 Kessels Road, Nathan, QLD 4111, Australia
| | - E Campbell
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
- ProDelphinus, Jose Galvez 780e, Miraflores, Perú
| | - MID Carter
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
| | - T Collins
- Wildlife Conservation Society, 2300 Southern Blvd., Bronx, NY 10460, USA
| | - RJC Currey
- Marine Stewardship Council, 1 Snow Hill, London, EC1A 2DH, UK
| | - C Domit
- Laboratory of Ecology and Conservation, Marine Study Center, Universidade Federal do Paraná, Brazil
| | - V Franco-Trecu
- Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Uruguay
| | - MMPB Fuentes
- Marine Turtle Research, Ecology and Conservation Group, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USA
| | - E Gilman
- Pelagic Ecosystems Research Group, Honolulu, HI 96822, USA
| | - RG Harcourt
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - EM Hines
- Estuary & Ocean Science Center, San Francisco State University, 3150 Paradise Dr. Tiburon, CA 94920, USA
| | - AR Hoelzel
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - SK Hooker
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
| | - DW Johnston
- Duke Marine Lab, 135 Duke Marine Lab Road, Beaufort, NC 28516, USA
| | - N Kelkar
- Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, Karnataka, India
| | - JJ Kiszka
- Department of Biological Sciences, Coastlines and Oceans Division, Institute of Environment, Florida International University, Miami, FL 33199, USA
| | - KL Laidre
- Polar Science Center, APL, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, USA
| | - JC Mangel
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
- ProDelphinus, Jose Galvez 780e, Miraflores, Perú
| | - H Marsh
- James Cook University, Townsville, QLD 48111, Australia
| | - SM Maxwell
- School of Interdisciplinary Arts and Sciences, University of Washington Bothell, Bothell WA 98011, USA
| | - AB Onoufriou
- School of Biology, University of St Andrews, Fife, KY16 8LB, UK
- Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - DM Palacios
- Marine Mammal Institute, Hatfield Marine Science Center, Oregon State University, Newport, OR, 97365, USA
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97330, USA
| | - GJ Pierce
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
- Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Cientificas, Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain
| | - LS Ponnampalam
- The MareCet Research Organization, 40460 Shah Alam, Malaysia
| | - LJ Porter
- SMRU Hong Kong, University of St. Andrews, Hong Kong
| | - DJF Russell
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, KY16 8LB, UK
- Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Fife, KY16 8LB, UK
| | - KA Stockin
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North, New Zealand
| | - D Sutaria
- School of Interdisciplinary Arts and Sciences, University of Washington Bothell, Bothell WA 98011, USA
| | - N Wambiji
- Kenya Marine and Fisheries Research Institute, P.O. Box 81651, Mombasa-80100, Kenya
| | - CR Weir
- Ketos Ecology, 4 Compton Road, Kingsbridge, Devon, TQ7 2BP, UK
| | - B Wilson
- Scottish Association for Marine Science, Oban, Argyll, PA37 1QA, UK
| | - BJ Godley
- Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK
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Bamford CCG, Kelly N, Dalla Rosa L, Cade DE, Fretwell PT, Trathan PN, Cubaynes HC, Mesquita AFC, Gerrish L, Friedlaender AS, Jackson JA. A comparison of baleen whale density estimates derived from overlapping satellite imagery and a shipborne survey. Sci Rep 2020; 10:12985. [PMID: 32737390 PMCID: PMC7395155 DOI: 10.1038/s41598-020-69887-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 07/07/2020] [Indexed: 01/22/2023] Open
Abstract
As whales recover from commercial exploitation, they are increasing in abundance in habitats that they have been absent from for decades. However, studying the recovery and habitat use patterns of whales, particularly in remote and inaccessible regions, frequently poses logistical and economic challenges. Here we trial a new approach for measuring whale density in a remote area, using Very-High-Resolution WorldView-3 satellite imagery. This approach has capacity to provide sightings data to complement and assist traditional sightings surveys. We compare at-sea whale density estimates to estimates derived from satellite imagery collected at a similar time, and use suction-cup archival logger data to make an adjustment for surface availability. We demonstrate that satellite imagery can provide useful data on whale occurrence and density. Densities, when unadjusted for surface availability are shown to be considerably lower than those estimated by the ship survey. However, adjusted for surface availability and weather conditions (0.13 whales per km2, CV = 0.38), they fall within an order of magnitude of those derived by traditional line-transect estimates (0.33 whales per km2, CV = 0.09). Satellite surveys represent an exciting development for high-resolution image-based cetacean observation at sea, particularly in inaccessible regions, presenting opportunities for ongoing and future research.
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Affiliation(s)
- C C G Bamford
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK. .,University of Southampton, University Road, Southampton, SO17 1BJ, UK.
| | - N Kelly
- Australian Antarctic Division, Department of Agriculture, Water and the Environment, Australian Government, Channel Highway, Kingston, 7050, Australia
| | - L Dalla Rosa
- Laboratório de Ecologia e Conservação da Megafauna Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande-FURG, Av. Itália km.8, Rio Grande, RS, 96203-900, Brazil
| | - D E Cade
- Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, 93950, USA.,Institute for Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95006, USA
| | - P T Fretwell
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - P N Trathan
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - H C Cubaynes
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - A F C Mesquita
- Laboratório de Ecologia e Conservação da Megafauna Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande-FURG, Av. Itália km.8, Rio Grande, RS, 96203-900, Brazil
| | - L Gerrish
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - A S Friedlaender
- Institute for Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95006, USA
| | - J A Jackson
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
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Barnas AF, Darby BJ, Vandeberg GS, Rockwell RF, Ellis-Felege SN. A comparison of drone imagery and ground-based methods for estimating the extent of habitat destruction by lesser snow geese (Anser caerulescens caerulescens) in La Pérouse Bay. PLoS One 2019; 14:e0217049. [PMID: 31398201 PMCID: PMC6688855 DOI: 10.1371/journal.pone.0217049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 05/05/2019] [Indexed: 11/18/2022] Open
Abstract
Lesser snow goose (Anser caerulescens caerulescens) populations have dramatically altered vegetation communities through increased foraging pressure. In remote regions, regular habitat assessments are logistically challenging and time consuming. Drones are increasingly being used by ecologists to conduct habitat assessments, but reliance on georeferenced data as ground truth may not always be feasible. We estimated goose habitat degradation using photointerpretation of drone imagery and compared estimates to those made with ground-based linear transects. In July 2016, we surveyed five study plots in La Pérouse Bay, Manitoba, to evaluate the effectiveness of a fixed-wing drone with simple Red Green Blue (RGB) imagery for evaluating habitat degradation by snow geese. Ground-based land cover data was collected and grouped into barren, shrub, or non-shrub categories. We compared estimates between ground-based transects and those made from unsupervised classification of drone imagery collected at altitudes of 75, 100, and 120 m above ground level (ground sampling distances of 2.4, 3.2, and 3.8 cm respectively). We found large time savings during the data collection step of drone surveys, but these savings were ultimately lost during imagery processing. Based on photointerpretation, overall accuracy of drone imagery was generally high (88.8% to 92.0%) and Kappa coefficients were similar to previously published habitat assessments from drone imagery. Mixed model estimates indicated 75m drone imagery overestimated barren (F2,182 = 100.03, P < 0.0001) and shrub classes (F2,182 = 160.16, P < 0.0001) compared to ground estimates. Inconspicuous graminoid and forb species (non-shrubs) were difficult to detect from drone imagery and were underestimated compared to ground-based transects (F2,182 = 843.77, P < 0.0001). Our findings corroborate previous findings, and that simple RGB imagery is useful for evaluating broad scale goose damage, and may play an important role in measuring habitat destruction by geese and other agents of environmental change.
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Affiliation(s)
- Andrew F. Barnas
- University of North Dakota, Department of Biology, Grand Forks, North Dakota, United States of America
- * E-mail:
| | - Brian J. Darby
- University of North Dakota, Department of Biology, Grand Forks, North Dakota, United States of America
| | - Gregory S. Vandeberg
- University of North Dakota, Department of Geography & Geographic Information Science, Grand Forks, North Dakota, United States of America
| | - Robert F. Rockwell
- American Museum of Natural History, Vertebrate Zoology, New York, New York, United States of America
| | - Susan N. Ellis-Felege
- University of North Dakota, Department of Biology, Grand Forks, North Dakota, United States of America
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